Overfished ecosystem held together by a single species

When an ecosystem becomes overfished, some species may be able to step in and …

When an ecosystem becomes overfished, some species may be able to step in and fill the food chain gaps until others can recover, according to a new study published in Science. The bearded goby, a fish that lives off the coast of southwest Africa, has become the predominant prey species in the area because the rest have been overfished. The goby should be threatened under the weight of so many predators, but it isn't—in fact, researchers find it's doing better than ever, thanks to its ability to adapt while supporting the rest of the region's food chain.

The coast of southwest Africa used to be home to one to some of the most successful fisheries in the world. Fishing boats collected huge amounts of sardines and anchovies, the base of any self-respecting predator's food pyramid, until the species became heavily overfished. Now, the waters are dominated by jellyfish, unsuitable for eating by most predators in the area.

With the anchovies and sardines gone, all the predators have turned to one of the only small fish species left: the four-inch long bearded goby. The pressure of predation, combined with an increase in poisonous chemicals like hydrogen sulfides and methane in the water (which are only expected to increase with climate change) should have put the goby in danger of extinction. But the opposite has turned out to be true: somehow, the bearded goby population is just fine.

The idea of an ecosystem not suffering under the consequences of overfishing was baffling to researchers. In 2008, a large team of scientists set out to collect several types of data to figure out how the goby was surviving, even thriving.

They used acoustic imaging of the ocean at all hours of the day and night to see the goby's behavior patterns, trawled some fish themselves to open them up and see what they were eating, and chemically analyzed the water columns and sediment in the area. The researchers also set up controlled experiments with live goby specimens to test their reactions to various environmental factors.

What they were able to determine from their data was that the goby was in some ways suited to survive the situation it was in. But in others, the goby had adapted, and has actually bridged together some of the ocean's resources to help the area recover.

One of the goby's characteristics that has proved invaluable to its survival was its ability to tolerate chemically altered waters. The area has high levels of hydrogen sulfides and sinking levels of oxygen, especially down on the ocean floor. Not only could the goby live in this chemistry, it could also use it to its advantage.

Typically, when fish spend too much time in low-oxygen waters, they sustain brain and heart damage. One of the goby's predators, the hake, suffers permanent heart damage in this kind of environment.

The goby fared much better in these conditions—it still has quick escape responses, even after several hours of low oxygen supply, and its heart performance could recover with more oxygen in a couple of hours. This tolerance for the low-oxygen ocean floor gives the goby somewhere to hide from predators.

While the goby don't mind a lack of oxygen for a little while, they do need to replenish themselves regularly. Researchers observed that the species has learned to bury itself in the ocean mud during the day, and then swim up to more oxygenated waters at night to restore themselves, and possibly help them digest what may have been its biggest change: its diet.

When researchers opened up a couple of the fish to see the contents of their stomachs, they found that the goby had been eating the jellyfish that had become plentiful. They speculated the goby could be eating dead or sick jellyfish that had drifted to the bottom, or taking nibbles off live ones when they go up to the oxygenated waters at night.

Aside from the jellyfish, the goby also appear to be eating the diatomaceous mud that rests on the ocean floor, which includes decomposed plants, animals, and bacteria. The authors estimate the goby's diet is about 34 percent mud and as much as 60 percent jellyfish. It's effectively using food chain "dead ends" to fuel its numbers and sustain predator populations.

While the goby is doing all right now, researchers are unsure what its long term fate will be. They note that climate change will ramp up the inflow of low-oxygen waters, which may eliminate any gains in population that predators derive from the goby abundance.

Still, predators that survive the hostile water chemistry will need something to eat, and the bearded goby is likely to continue churning ocean waste into useable biomass. Species like the goby may be the difference between an ocean ecosystem that pulls through climate change and other human impacts, and an ecosystem that falls apart.

Change favors generalists, news at 11. And no, its people who like eating who favor species as they are. Unless you're a business who takes advantage of someone else's stupidity, then its an opportunity.

>> The idea of an ecosystem not suffering under the consequences of overfishing was baffling to researchers.

Well the ecosystem suffered. Anchovies and sardines disappeared. And as the scientists themselves claim, they are unsure of the long term fate of the goby (and I'll add: for that matter, of the whole ecosystem).

I'm happy for that particular species of gobies. Tough little bastard. But we don't know exactly how well this species is going to fare or how competent it will be in supplying the food chain. Do we have data on their predators? Are their numbers declining, increasing, remaining stationary? Can the gobies new diet affect their own health? What's the status on the jellyfish? Are their numbers increasing too much? Are these healthy or there are too many sick or dying?

if there is anything left to evolve from. Thats the thing, we have become so efficient at catching prey that unless we restrain ourselves, there will be nothing left that can evolve to fill a vacant slot in the pyramid.

It is only environmentalists who stick to this crazy idea that somehow humans should freeze ecosystems as they are, and allow no change, and reintroduce species all that costly and crazy stuff.

I don't think that environmentalist want to freeze ecosystems the way they are. I think they realize that small species can adapt more quickly. In most mass extinction events, it is the large megafauna which dies off first.

It is only environmentalists who stick to this crazy idea that somehow humans should freeze ecosystems as they are, and allow no change, and reintroduce species all that costly and crazy stuff.

A fishery managed for sustainability is most certainly not freezing things as they are, and it might be the only thing that keeps us from having nothing but jellyfish to eat after we've turned and overfished the gobies. In your strawman filled world, does that make me an environmentalist?

I don't think that environmentalist want to freeze ecosystems the way they are. I think they realize that small species can adapt more quickly.

Well, there's a bunch of government agencies making a living for a bunch of bureaucrats by blocking a bunch of projects because small species such as the Minor Western Grayish-Green-Blue Jumping Horned Snail are supposed to be present in any given plot of land.

So I am not sure they share your opinion that small species adapt quickly.

Regarding environmentalists' nutty notions of an imagined, unchanging, frozen-in-time Eden, you may wish to read "Playing God in Yellowstone: The Destruction of America's First National Park."

first of all i am not a right wing conservative (with all the hostility in the forums i would rather that not be assumed)...i agree we very well may be damaging the earth at a rate in which it may not be able to recover...but...

the way this article was written really makes it hard for me to enjoy...i really love good news regarding the way our planet is able to adapt...unfortunately the writer makes me feel like despite this good news its all doom and gloom...why make this into a depressing "climate change is going to destroy us all" type of article when this study goes to show that even with scientists expecting the ecosystem around africa's fisheries to be in a state of deterioration...it seems that these ecosystems are quite healthy, in spite of all foreboding hypothesis...

i know that this site promotes good science...but cant we be a little more optimistic about these kind of stories...its nice to know that the earth may be a lot more resilient than we have given it credit for...

More and more I am convinced that we will be switching over to farmed fish for 100% of our seafood needs in the coming decades. Think about it, when it comes down to it, fisherman are hunter-gatherers - extremely sophisticated hunter-gatherers - but even with the best equipment, they simply cannot match the efficiency of a farm.

first of all i am not a right wing conservative (with all the hostility in the forums i would rather that not be assumed)...i agree we very well may be damaging the earth at a rate in which it may not be able to recover...but...

the way this article was written really makes it hard for me to enjoy...i really love good news regarding the way our planet is able to adapt...unfortunately the writer makes me feel like despite this good news its all doom and gloom...why make this into a depressing "climate change is going to destroy us all" type of article when this study goes to show that even with scientists expecting the ecosystem around africa's fisheries to be in a state of deterioration...it seems that these ecosystems are quite healthy, in spite of all foreboding hypothesis...

i know that this site promotes good science...but cant we be a little more optimistic about these kind of stories...its nice to know that the earth may be a lot more resilient than we have given it credit for...

To not mention how climate change is effecting fish populations would be a huge disservice to science. It is also hard to distinguish by what you mean by “planet is adaptable” This could mean that our planet – the huge ball of water and rock (or) planet- the ecosystem. The planet and the animals that live on the planet are adaptable to a certain extent, but will face certain extinction if their environment rapidly changes, the planet the ball of rock has been here for millions of years supporting life and is probably not going anywhere. If we look at our planet- the ecosystem this type of stuff is becoming increasingly common. Large populations of fish species have dwindled causing trouble for the fishing industry as a whole. If overfishing was not enough, we now have changing chemical compositions in the ocean making it very hard for fish to adapt and survive. Saying that the oceans are all roses and rainbows when they are not is best suited to conservative news.

Wait a minute! So, a single fish is doing better than expected. Well, by all means we need to stop any efforts to protect the environment. After all, these scientist just proved that nothing we humans do will actually hurt the environment. Everyone else is just conspiracy theorist.

Sheesh, both sides of this debate are ridiculous sometimes. The truth is somewhere in the middle. Humans don't cause everything that changes on the Earth, but to think that we have no affect at all is just as stupid.

More and more I am convinced that we will be switching over to farmed fish for 100% of our seafood needs in the coming decades. Think about it, when it comes down to it, fisherman are hunter-gatherers - extremely sophisticated hunter-gatherers - but even with the best equipment, they simply cannot match the efficiency of a farm.

With the ever increasing population of man, I have no doubt. Not to mention, everyone knows the best tasting fish are the ones that are kept in a small confining cages for their entire life and fed through an automatic feeding dispenser.

i am not saying its all roses and rainbows...simply pointing out that we dont have any idea how the earth is going to adapt to any amount of any stimulus until it actually happens...we expected the ecosystem to be very frail...from the article its quite the opposite...which still means that the part of the ecosystem that provided life for the larger fish species has been replaced with something else that is not so susceptible to either fishing or other chemical and temperature changes in the water...

i am not saying that we should just go fish to our hearts content without oversight and regulation, or that there is no damage to report...just simply...life (i hope the term life is specific enough to not just mean the rocks of the earth) adapts...

am i mistaken that this is generally great news for the survival of all species on earth including humans??? then why do i feel bad about myself after reading this article...this is positive science...right??? or is there such a thing anymore when it comes to environmental science and environmental reporting??? perhaps bad news just sells better???

i dont think im gonna respond on this section anymore...i know people are just going to take my serious criticism with the article as me being an uninformed troll...i am far from it...i just wish that sometimes science would stick to science instead of op ed's...im not sure if the ars writer added the negative tone or if he surmised it from the original article...i just wish news like this would be placed in the "good news" section of science for those of us holding out hope that we can still maintain balance with the earth...

i am not saying its all roses and rainbows...simply pointing out that we dont have any idea how the earth is going to adapt to any amount of any stimulus until it actually happens...we expected the ecosystem to be very frail...from the article its quite the opposite...which still means that the part of the ecosystem that provided life for the larger fish species has been replaced with something else that is not so susceptible to either fishing or other chemical and temperature changes in the water...

i am not saying that we should just go fish to our hearts content without oversight and regulation, or that there is no damage to report...just simply...life (i hope the term life is specific enough to not just mean the rocks of the earth) adapts...

am i mistaken that this is generally great news for the survival of all species on earth including humans??? than why do i feel bad about myself after reading this article...this is positive science...right??? or is there such a thing anymore when it comes to environmental science and environmental reporting??? perhaps bad news just sells better???

Its a well know fact in reporting that negative news sells more papers than positive, –so I know how you feel. I dont think this article by itself is particularily depressing, but it is depressing to read that the Gobi can/has to make such adaptions in lue of other fish that would typically be found in its area. I would wish for a world where sustainability and balancing play major roles in the ecosystem, but I would only be diluding myself into think such a world could exist.

On the subject of farmed fish, even that has to be done very delicately.

For one, humans tend to like eating top predators (more meat) and these tend to be migratory or have large ranges. When we then farm them then we have to feed them something and that sadly tends to be small fish we don't like - such as this goby. This means we harvest huge amounts of fish from low in the web and feed them to our preferred eating with it's implicit impact on the ecosystem that the fish came from.

The second issue is the problem of waste. Farming leads to high concentrations of animals and that leads to high concentrations of waste. This can lead to a radical change in chemical makeup of the farm's aquatic locality - even if it's built in a current, it just goes up stream. This can lead to a local eutrophication and the end of the ecosystem that was there before.

I'm not say we can't farm fish, I'm just saying we know enough now to know we need to know the impacts of what we do. It's our responsibility

On the subject of ecosystem maintenance, my view is that if the system is changing naturally then let it go - and this applies to extinctions. If however, man has changed the ecosystem (species introduction, ecosystem destruction, pollution, fishing) then it (once again) is our responsibility to tidy our own mess. I appreciate that this can be a fine line to find now we act on a global scale.

Not only does it sell better, alarmism helps to drive funding to research "the problem," and to set up new bureaucracies to monitor and regulate the problem. It is also a nice cover for politicians to be seen "doing something."

It is all to the good for journalists, bureaucrats, researchers, and politicians.

Taxpayers, ahh, maybe not so much. But you can't make all the people happy all the time, can you?

More and more I am convinced that we will be switching over to farmed fish for 100% of our seafood needs in the coming decades. Think about it, when it comes down to it, fisherman are hunter-gatherers - extremely sophisticated hunter-gatherers - but even with the best equipment, they simply cannot match the efficiency of a farm.

its being worked on. Salmon is more and more being "farmed", while cod is proving more difficult as its more picky about its habitat or something.

btw, there is one problem in all of this and thats the issue of international waters.

It is only environmentalists who stick to this crazy idea that somehow humans should freeze ecosystems as they are, and allow no change, and reintroduce species all that costly and crazy stuff.

That whoosh you hear is the point going over your head. It's not about "environmentalists." It's about the shit we eat.

Exactly. Xavierltzmann clearly has it in his head that there's a massive environmentalist-government conspiracy out to use taxpayer money to create useless inefficient jobs.

I think what people need to take away from articles like this is one simple thing. HUMANS ARE TERRIBLE AT PREDICTING COMPLEX SYSTEMS. It's yet another article where people extensively study a complex issue and conclude, "Well, XYZ is certainly happening, but we don't know what will happen in the future."

Nobody knows what will happen in ocean ecosystems any better than they know what will happen in a stock market, and often, the "experts" who think they know what's going to happen are among the MOST WRONG.

Think about the limits of knowledge and what those limits mean. Our brains are set up to make small predictions constantly, but when things get above a certain level of complexity, we are terrible at it. If you accept that you can't predict what's going to happen, you're going to make significantly different decisions compared to someone who takes data XYZ and uses it to make bell curve predictions that "rule out" the possibility of unlikely events.

Just because some fish species is adapting doesn't mean everything's going to be fine. That's like looking at the stock market before a crash and saying, "Look, it's going up...surely it will go up tomorrow! Ask the turkey at the farm on the day before Thanksgiving if it's going to get fed again the next day.

Don't be a turkey. (Read "The Black Swan" and try not to let the point woosh over your head".)

The point is that during rapid change, adaptive and/or generalist species do better. During slower times, specialists who can handle ecological niches better thrive.

The problem, from a human point of view - we like our specialists. They're delicious. We'd rather eat a tuna than a jellyfish. Or a sunfish. Seagull or crow are both highly adaptable species, but darnit, they just don't taste all that good. You're more than welcome to eat crow, though.

Nobody knows what will happen in ocean ecosystems any better than they know what will happen in a stock market, and often, the "experts" who think they know what's going to happen are among the MOST WRONG.

[...]

Just because some fish species is adapting doesn't mean everything's going to be fine.

I love it how the case is made that nobody knows what will happen in ecosystems. It would seem therefore that the logical conclusion is that because we don't know, the best approach may be a hands-off approach because nobody knows, or perhaps assume that everything's going to be fine, given that we have proof thru this very study that the ecosystem autonomously found an alternate equilibrium point.

Instead, a logic jump is made, and we are asked in the face of opposite evidence to consider that we go the pessimist route and assume that not everything is going to be fine.

Man, on reading this article I was all geared up to post a comment predicting Xavier would jump in, trumpet the good news that mankind can't hurt the environment, trawl baby trawl! and totally miss the point that the environment under discussion is already diminished and close to collapse, even if one species of goby is thriving (imagine if we drove all the prey animals in North America to extinction and they were supplanted by an explosion of rats! Good news, everyone!) Then I see he did essentially that in the very first post. Damn!

What are the principle causes for the low-O and high-H2S conditions around coast? Are they technically hypoxic or not there yet?

I love it how the case is made that nobody knows what will happen in ecosystems. It would seem therefore that the logical conclusion is that because we don't know, the best approach may be a hands-off approach because nobody knows, or perhaps assume that everything's going to be fine, given that we have proof thru this very study that the ecosystem autonomously found an alternate equilibrium point.

Everything is not going to be fine if you like sardines and anchovies. That's one of the points you keep totally skipping over with your logic jumps.

Nobody knows what will happen in ocean ecosystems any better than they know what will happen in a stock market, and often, the "experts" who think they know what's going to happen are among the MOST WRONG.

[...]

Just because some fish species is adapting doesn't mean everything's going to be fine.

I love it how the case is made that nobody knows what will happen in ecosystems. It would seem therefore that the logical conclusion is that because we don't know, the best approach may be a hands-off approach because nobody knows, or perhaps assume that everything's going to be fine, given that we have proof thru this very study that the ecosystem autonomously found an alternate equilibrium point.

Instead, a logic jump is made, and we are asked in the face of opposite evidence to consider that we go the pessimist route and assume that not everything is going to be fine.

How twisted is that?

I always try to be as cautious as possible when drawing conclusions. For instance, I don’t think you can take away from the article that the system is at equilibrium. All it says is that the Gobi fish is doing well despite what is happening with other species of fish with similar size which are not (due to various reasons)

We must also analyze what “doing fine” is/means.

Is it fine that other fish are struggling just as long as one type is doing ok?Is it fine that there are such low numbers of feeder fish for the rest of the ecosystem?Is it fine that we continue to disrupt the ecosystem and leave nature to clean up the mess?

I continually find it irksome that some people claim that a certain system is too complex to “know” anything about it. Almost 100 percent of the time they usually have no idea what they are talking about. Most natural systems that are of any significance are fairly well understood with always new stuff to learn, but simply not knowing everything does not mean we don’t know anything. Not knowing everything about a certain system also does not mean that we can’t use are current knowledge to make an accurate and informed prediction on future events. Rarely do scientists perform a study or do experiments where the outcome is completely mysterious(unable to even make an educated guess), it just doesn’t happen based on the way the scientific method evolved.

I challenge the clueless person who said “Nobody knows what will happen in ocean ecosystems any better than they know what will happen in a stock market”(this is not even an argument as it lacks a position, its just a complaint from a presummed whiner) to identify what sort of understanding would be necessary to study and make conclusions off of what is happening to the Gobi and other feeder fish in the area. I thought the conclusions already drawn seemed pretty sound and agreed with the evidence presented. Just because it wasn’t expected to happen doesn’t mean it wasn’t unthinkable to happen. Like nothing could have predicted this development…..oh please

Instead, a logic jump is made, and we are asked in the face of opposite evidence to consider that we go the pessimist route and assume that not everything is going to be fine.

When one is faced with a highly uncertain situation with potentially significant negative outcomes the only rational response is to act conservatively and err on the side of caution. If you wake up in an unknown pitch-black room and do not know how you got there, for instance, it is not smart to run around under the assumption that everything is fine and there is nothing there that you can bump into (or fall off from) and hurt yourself.

On a side note, there is a significant difference between human impact on the environment and the environmental impact of a major cataclysm. The direct shocks produced by cataclysms tend to be significant but rare. Sure, 90%, 95%, or even 99% of everything may die as a result, but whatever is lucky enough to remain gradually recovers and spends the next few million years flourishing.

Human impact on the other hand, tend to be smaller but more sustained. Not only does this mean that it is more difficult to immediately see our own impact than it is to see the impact of a massive asteroid smashing down, but it also means that by the time we are certain of our impact it may be too late to reverse anything because we have slowly but thoroughly suffocated everything beyond the point of recovery.

Furthermore, as many people have previously pointed out before me, the benefits of protecting the environment need not rely on any ethical or religious justifications. Ignoring the future for the sake of present-day convenience is simply unpragmatic. It is like taking a piss on your only source of fire because you were too lazy to turn around.

XavierItzmann is determined clearly to ignore evidence and assert his views. There is no point in trying to persuade him. Just ignore the troll.

The problem is simple: We humans are poor long-term thinkers and as mentioned before, poor at predicting complex systems. In the past, this has caused entire civilizations to collapse.

- Did anybody predict that the goby would surge in numbers before overfishing? Neither scientists nor fisherman, nor XavierItzmann did (assuming he has even heard of what a goby is before this).

- What about in the long run? Is this just a temporary spike? Nobody knows.

It's also important to consider the long term consequences of reduced biodiversity: vulnerability to change. When there are many species, there is a smaller chance that any one even will take out all of them. With one species making up a larger and larger proportion of the ecosystem, anything that could damage that one species' numbers could be bad for the entire ecosystem.

Even for fisherman, it is best to err on the side of caution, if only because you care about revenues from fish in the long term.

What are the principle causes for the low-O and high-H2S conditions around coast? Are they technically hypoxic or not there yet?

Yeah, I had the same questions as you did. Alas! I don't have access to the original document.

I was struck by the following datapoints:

1. This study is based on the pelagic fisheries off of SW Africa, presumably Namibia2. Namibia is one of the least densely populated countries in the world, i.e., where the heck are the H2S and presumably other contaminants coming from?3. The fishery collapse happened over 40 years ago.

At any rate, you gotta love the journalists and researchers who manage to shoehorn in a reference to OMG! Climate Change! into a piece about Spanish and Japanese and other developed-country overfishing off of the African coast.

I love it how the case is made that nobody knows what will happen in ecosystems. It would seem therefore that the logical conclusion is that because we don't know, the best approach may be a hands-off approach because nobody knows, or perhaps assume that everything's going to be fine, given that we have proof thru this very study that the ecosystem autonomously found an alternate equilibrium point.

Instead, a logic jump is made, and we are asked in the face of opposite evidence to consider that we go the pessimist route and assume that not everything is going to be fine.

How twisted is that?

I think I damn well know what happened: a loss of a good food source for protein and a loss of income for coastal populations. Maybe someone can explain to me how that is good.

And for the record... I do like jellyfish as a cold appetizer. But I also like anchovies.

It's also important to consider the long term consequences of reduced biodiversity: vulnerability to change. When there are many species, there is a smaller chance that any one even will take out all of them. With one species making up a larger and larger proportion of the ecosystem, anything that could damage that one species

Well, to be fair, it's the most adaptive species which survive when biodiversity is reduced. You don't see crows dying off, it's more things like ospreys.